Public broadcasting includes radio, television and other electronic media outlets whose primary mission is public service. It may be nationally or locally operated, depending on the country and the station. In some countries, public broadcasting is run by a single organization. Other countries have multiple public broadcasting organizations operating regionally or in different languages.

Historically, in many countries (with the notable exception of the U.S.), public broadcasting was once the only form or the dominant form of broadcasting. Commercial broadcasting now also exists in most of these countries.

Within public broadcasting there are two different views regarding commercial activity. One is that public broadcasting is incompatible with commercial objectives. The other is that public broadcasting can and should compete in the marketplace with commercial broadcasters.

Public broadcasters may receive their funding from an obligatory television license fee, voluntary individual contributions, government funding, or commercial sources. Public broadcasters do not rely on advertising to the same degree as commercial broadcasters, or at all; this allows public broadcasters to transmit programs that are not commercially viable to the mass market, such as public-affairs shows, radio and television documentaries, and educational programs.

One of the principles of public broadcasting is to provide coverage of interests for which there are missing or small markets. Public broadcasting attempts to cover topics of social benefit that are otherwise not be broadcast by commercial broadcasters.

Unless its independence is vigorously upheld, public broadcasting can become a tool of government, in the name of serving "the public interest."

Public Broadcasting in the United States

In the U.S., early public broadcasting stations were operated by state colleges and universities, and were often run as part of the schools' cooperative extension services. Stations were internally funded and did not rely on listener contributions to operate; some accepted advertising. Networks such as Iowa, South Dakota, and Wisconsin Public Radio began in this way.

In the United States, public broadcasting is decentralized and is not government-operated, but does receive some government support. Some of the funding comes from community support to hundreds of public radio and public television stations, each of which is an individual entity licensed to one of several different non-profit organizations, municipal or state governments, or universities. Sources of funding also include on-air and online pledge drives and the sale of underwriting "spots" (typically 15–30 seconds) to sponsors.

Public radio and television stations often produce their own programs; many also purchase additional programming from national producers and program distributors such as National Public Radio, Public Broadcasting Service, Public Radio International, American Public Television, American Public Media, and Public Radio Exchange. Federal government support for public radio and television is filtered through a separate organization, the Corporation for Public Broadcasting.

Public broadcasting is sometimes also referred to as public media, in an effort to capture the expansion of public broadcasting content from radio and television into digital technologies, in particular the web and mobile platforms. While some consider public media to be analogous to public broadcasting, others use the term more broadly to include all non-commercial media.

In the United States, the Public Broadcasting Service (PBS) (formerly National Educational Television) television network operates on a largely viewer-supported basis, with commercial sponsors of specific programs. Over time, sponsorship announcements ("underwriting") have slowly transformed into something resembling regular (commercial) TV advertisements, though they are usually shorter and have a more muted tone than what normally appears on commercial and cable TV. Underwriting may only issue declarative statements (including slogans) and may not include "calls to action." Most communities also have public-access television channels on local cable TV systems, which are generally paid for by cable television franchise fees and are sometimes supported in part through private donations.

There is considerable evidence that since the late 1960s, public broadcasting in the United States has had a pronounced leftist bias.

Radio

A public radio network, National Public Radio (NPR), was created in 1970, following the passage of the Public Broadcasting Act of 1967, which established the Corporation for Public Broadcasting. This network is colloquially though inaccurately conflated with public radio as a whole, when in fact public radio includes many organizations. Some independent local public radio stations buy their programming from distributors such as NPR, Public Radio International, American Public Media, Public Radio Exchange, and Pacifica Radio, most often distributed through the Public Radio Satellite System. Around these distributed programs, stations fill in varying amounts of local and other programming. A number of public stations are completely independent of these programming services, producing all or most of their content themselves.

Public radio stations in the U.S. tend to broadcast a mixture of news and talk radio programming along with some arts, culture, and music. Some of the larger operations split off these formats into separate stations or networks.

Local stations derive some of the funding for their operations through regular pledge drives seeking individual and corporate donations, and corporate underwriting. Some stations also derive a portion of their funding from federal, state and local governments and government-funded colleges and universities (in addition to receiving free use of the public radio spectrum). The local stations then contract with program distributors and also provide some programming themselves. NPR produces some of its own programming. NPR also receives some direct funding from private donors, foundations, and the Corporation for Public Broadcasting.